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Charlie
Asked: 2019-03-20 16:58:43 +0800 CST

Typical Geo Replication Lag for Azure GRS

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Microsoft Azure geo-redundant storage (GRS) is not instantaneous, so they expose a "last sync time" value to help users/admins understand the lag in geographic replication. Unfortunately the docs do not give any indication of how much lag is typical, so as a new user of Azure it's hard to know what to expect. Is it typically seconds, minutes, hours?

Clearly the ideal answer would be to perform some empirical tests, but for people who have already been using it, what type of lag do you typically see?

azure-storage

1 Answers

  1. Best Answer

    Minutes. In the link you provided, emphasis mine:

    Recovery Point Objective (RPO): In GRS and RA-GRS, the storage service asynchronously geo-replicates the data from the primary to the secondary location. In the event that the primary region becomes unavailable, you can perform an account failover (preview) to the secondary region. When you initiate a failover, recent changes that haven't yet been geo-replicated may be lost. The number of minutes of potential data that's lost is known as the RPO. The RPO indicates the point in time to which data can be recovered. Azure Storage typically has an RPO of less than 15 minutes, although there's currently no SLA on how long geo-replication takes.

    Measure this during your business continuity testing to confirm.

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